31 

    32 #include "libproc_impl.h"

    34 #ifndef __APPLE__

    36 #endif // __APPLE__

    42 

    43 typedef struct symtab_symbol {

    44   char *name;                // name like __ZThread_...

    45   uintptr_t offset;          // to loaded address

    46   uintptr_t size;            // size strlen

    47 } symtab_symbol;

    48 

    49 typedef struct symtab {

    50   char *strs;                // all symbols "__symbol1__'\0'__symbol2__...."

    51   size_t num_symbols;

    52   DB* hash_table;

    53   symtab_symbol* symbols;

    54 } symtab_t;

    55 

    56 #ifdef __APPLE__

    57 

    58 void build_search_table(symtab_t *symtab) {

    59   int i;

    60   for (i = 0; i < symtab->num_symbols; i++) {

    61     DBT key, value;

    62     key.data = symtab->symbols[i].name;

    63     key.size = strlen(key.data) + 1;

    64     value.data = &(symtab->symbols[i]);

    65     value.size = sizeof(symtab_symbol);

    66     (*symtab->hash_table->put)(symtab->hash_table, &key, &value, 0);

    67 

    68     // check result

    69     if (is_debug()) {

    70       DBT rkey, rvalue;

    71       char* tmp = (char *)malloc(strlen(symtab->symbols[i].name) + 1);

    72       strcpy(tmp, symtab->symbols[i].name);

    73       rkey.data = tmp;

    74       rkey.size = strlen(tmp) + 1;

    75       (*symtab->hash_table->get)(symtab->hash_table, &rkey, &rvalue, 0);

    76       // we may get a copy back so compare contents

    77       symtab_symbol *res = (symtab_symbol *)rvalue.data;

    78       if (strcmp(res->name, symtab->symbols[i].name)  ||

    79           res->offset != symtab->symbols[i].offset    ||

    80           res->size != symtab->symbols[i].size) {

    81         print_debug("error to get hash_table value!\n");

    82       }

    83       free(tmp);

    84     }

    85   }

    86 }

    87 

    88 // read symbol table from given fd.

    89 struct symtab* build_symtab(int fd) {

    90   symtab_t* symtab = NULL;

    91   int i;

    92   mach_header_64 header;

    93   off_t image_start;

    94 

    95   if (!get_arch_off(fd, CPU_TYPE_X86_64, &image_start)) {

    96     print_debug("failed in get fat header\n");

    97     return NULL;

    98   }

    99   lseek(fd, image_start, SEEK_SET);

   100   if (read(fd, (void *)&header, sizeof(mach_header_64)) != sizeof(mach_header_64)) {

   101     print_debug("reading header failed!\n");

   102     return NULL;

   103   }

   104   // header

   105   if (header.magic != MH_MAGIC_64) {

   106     print_debug("not a valid .dylib file\n");

   107     return NULL;

   108   }

   109 

   110   load_command lcmd;

   111   symtab_command symtabcmd;

   112   nlist_64 lentry;

   113 

   114   bool lcsymtab_exist = false;

   115 

   116   long filepos = ltell(fd);

   117   for (i = 0; i < header.ncmds; i++) {

   118     lseek(fd, filepos, SEEK_SET);

   119     if (read(fd, (void *)&lcmd, sizeof(load_command)) != sizeof(load_command)) {

   120       print_debug("read load_command failed for file\n");

   121       return NULL;

   122     }

   123     filepos += lcmd.cmdsize;  // next command position

   124     if (lcmd.cmd == LC_SYMTAB) {

   125       lseek(fd, -sizeof(load_command), SEEK_CUR);

   126       lcsymtab_exist = true;

   127       break;

   128     }

   129   }

   130   if (!lcsymtab_exist) {

   131     print_debug("No symtab command found!\n");

   132     return NULL;

   133   }

   134   if (read(fd, (void *)&symtabcmd, sizeof(symtab_command)) != sizeof(symtab_command)) {

   135     print_debug("read symtab_command failed for file");

   136     return NULL;

   137   }

   138   symtab = (symtab_t *)malloc(sizeof(symtab_t));

   139   if (symtab == NULL) {

   140     print_debug("out of memory: allocating symtab\n");

   141     return NULL;

   142   }

   143 

   144   // create hash table, we use berkeley db to

   145   // manipulate the hash table.

   146   symtab->hash_table = dbopen(NULL, O_CREAT | O_RDWR, 0600, DB_HASH, NULL);

   147   if (symtab->hash_table == NULL)

   148     goto quit;

   149 

   150   symtab->num_symbols = symtabcmd.nsyms;

   151   symtab->symbols = (symtab_symbol *)malloc(sizeof(symtab_symbol) * symtab->num_symbols);

   152   symtab->strs    = (char *)malloc(sizeof(char) * symtabcmd.strsize);

   153   if (symtab->symbols == NULL || symtab->strs == NULL) {

   154      print_debug("out of memory: allocating symtab.symbol or symtab.strs\n");

   155      goto quit;

   156   }

   157   lseek(fd, image_start + symtabcmd.symoff, SEEK_SET);

   158   for (i = 0; i < symtab->num_symbols; i++) {

   159     if (read(fd, (void *)&lentry, sizeof(nlist_64)) != sizeof(nlist_64)) {

   160       print_debug("read nlist_64 failed at %i\n", i);

   161       goto quit;

   162     }

   163     symtab->symbols[i].offset = lentry.n_value;

   164     symtab->symbols[i].size  = lentry.n_un.n_strx;        // index

   165   }

   166 

   167   // string table

   168   lseek(fd, image_start + symtabcmd.stroff, SEEK_SET);

   169   int size = read(fd, (void *)(symtab->strs), symtabcmd.strsize * sizeof(char));

   170   if (size != symtabcmd.strsize * sizeof(char)) {

   171      print_debug("reading string table failed\n");

   172      goto quit;

   173   }

   174 

   175   for (i = 0; i < symtab->num_symbols; i++) {

   176     symtab->symbols[i].name = symtab->strs + symtab->symbols[i].size;

   177     if (i > 0) {

   178       // fix size

   179       symtab->symbols[i - 1].size = symtab->symbols[i].size - symtab->symbols[i - 1].size;

   180       print_debug("%s size = %d\n", symtab->symbols[i - 1].name, symtab->symbols[i - 1].size);

   181 

   182     }

   183 

   184     if (i == symtab->num_symbols - 1) {

   185       // last index

   186       symtab->symbols[i].size =

   187             symtabcmd.strsize - symtab->symbols[i].size;

   188       print_debug("%s size = %d\n", symtab->symbols[i].name, symtab->symbols[i].size);

   189     }

   190   }

   191 

   192   // build a hashtable for fast query

   193   build_search_table(symtab);

   194   return symtab;

   195 quit:

   196   if (symtab) destroy_symtab(symtab);

   197   return NULL;

   198 }

   199 

   200 #else // __APPLE__

   370   }